1. Field of the Invention
The present invention relates to a holding member, a driving apparatus, a pickup apparatus, and a disc apparatus.
2. Description of the Related Art
FIG. 7 is a perspective view illustrating an embodiment of a holding member, driving apparatus, and pickup apparatus, FIG. 8 is a perspective view illustrating the holding member, FIG. 9 is an explanatory diagram of a portion of the driving apparatus, and FIG. 10 is also an explanatory diagram of a portion of the driving apparatus.
A coil 540 (FIGS. 7, 9, 10) is made up such that a substantially linear conductor is directly wound around a coil mounting portion 520 of a lens holding member 510 (FIG. 8), so-called lens holder 510. The substantially flat-plate-shaped coil 540 in a substantially rectangular annular shape is made up such that the substantially linear conductor is directly wound around the coil mounting portion 520 of the lens holder 510 (FIG. 7). The coil mounting portion 520 of the lens holder 510 of a type depicted in FIGS. 7 and 8 includes wire-wound flange portions 523, 524 that prevent the coil 540 formed by winding the conductor from being accidentally detached from a coil supporting unit 529 of the coil mounting portion 520.
For example, in the case where a driving apparatus 505 (FIG. 9) of an optical pickup apparatus 503 (FIG. 7) is in an initial state, or an objective lens is in a focused position for a signal layer of an optical disc (all not depicted), the coil 540 making up the driving apparatus 505, so-called actuator 505, is in such a neutral state as to be in a substantially vertically middle position relative to magnets 80, 90 facing the coil 540 when a portion of the actuator 505 is viewed laterally from inside to outside, for example.
A actuator of an optical pickup apparatus includes an actuator of an optical head made up such that an air-core focus coil is formed by winding around a rectangular objective lens holder, flat tracking coils are bonded to two surfaces thereof that are the opposing sides of the objective lens holder and in positions opposing to each other, and a black ground glass plate materials are bonded to the focusing coil adjacently thereto, for example, (see Japanese Patent Application Laid-Open Publication No. 08-129767 pp. 1 and 3 to 4, FIGS. 1 to 3, for example).
The actuator of the optical head depicted in the above Patent Document is described as a type of an actuator of the optical pickup apparatus in which the wire-wound flange portion for fixing the flat tracking coil is not required for the objective lens holder.
However, it has been considered to be difficult to further improve the sensitivity of the coil 540 to the magnets 80, 90, with the holding member 510 (FIGS. 7 and 8), the driving apparatus 505 (FIGS. 7 to 10), and the pickup apparatus 503 (FIGS. 7 and 8).
In the lens holder 510 of such a type that the coil 540 is made up by directly winding the substantially linear conductor around the coil mounting portion 520 of the lens holder 510, the wire-wound flange portions 523, 524, which prevents the coil 540 formed by winding from being accidentally detached from the coil supporting portion 529, are formed extending from the coil supporting unit 529 (FIG. 8) of the coil mounting portion 520, and thus, the magnets 80, 90 (FIGS. 9 and 10) facing the coil 540 are kept away from the coil 540 (FIG. 7) by the thickness of the wire-wound flange portions 523, 524 (FIGS. 7 and 8).
When the magnets 80, 90 (FIGS. 9 and 10) are kept away from the coil 540 (FIGS. 7, 9, and 10), it becomes difficult to effectively use the magnetic field generated from the magnets 80, 90, so that the magnetic field is wastefully used. Therefore, a loss of sensitivity is caused in the magnets 80, 90 and the coil 540. Since an unnecessary clearance, so-called gap is created between the magnets 80, 90 (FIGS. 9 and 10) and the coil 540 by the thickness of the wire-wound flange portions 523, 524 (FIGS. 7 and 8), the magnetic field generated from the magnets 80, 90 is not effectively utilized and a loss of sensitivity is caused in the magnets 80, 90 and the coil 540.
As a measure, such a configuration has been conceived that has an air-core tracking coil adhered to a focus coil formed by winding around an objective lens holder as described in the above Patent Document, for example. However, if an air-core tracking coil is adhered to a focus coil formed by winding around a lens holder, since no positioning portion exists for positioning and mounting on the focus coil the air-core tracking coil provided separately from the lens holder and the focus coil, the mounting operation of the air-core tracking coil is very difficult, which is considered to be a problem.
In association with the fact that the mounting operation of the air-core tracking coil is very difficult, it is also considered to be a problem that the cost becomes very high for the assembly operation of the air-core tracking coil to the focus coil.
As illustrated in FIG. 7, the substantially rectangular annular coil 540 is made up by directly winding the substantially linear conductor around the coil mounting portion 520 of the lens holder 510 and is formed in a substantially flat plate shape.
In the case where a whole of a first flat surface portion 541 of the substantially flat-plate-shaped coil 540 in a substantially rectangular annular shape is located over a whole of a flat surface portion 81 of the first substantially flat-plate-shaped magnet 80 (FIG. 9) with a predetermined distance in a substantially uniform manner, where the first flat surface portion 541 of the substantially flat-plate-shaped coil 540 in a substantially rectangular annular shape is disposed substantially parallel to the flat surface portion 81 of the first substantially flat-plate-shaped magnet 80, where a whole of a second flat surface portion 542 of the substantially flat-plate-shaped coil 540 in a substantially rectangular annular shape is located over a whole of a flat surface portion 92 of the second substantially flat-plate-shaped magnet 90 with a predetermined distance in a substantially uniform manner, and where the second flat surface portion 542 of the substantially flat-plate-shaped coil 540 in a substantially rectangular annular shape is disposed substantially parallel to the flat surface portion 92 of the second substantially flat-plate-shaped magnet 90; when a movable unit 507 including the coil 540 of the actuator 505 is moved substantially along an up-and-down direction D1, for example (FIG. 10), a substantially curved first end 543a on the upper side of the substantially rectangular annular coil 540 may be located above an upper end surface portion 83 of the substantially flat-plate-shaped first magnet 80, and a substantially curved second end 543b on the upper side of the substantially rectangular annular coil 540 may be located above an upper end surface portion 93 of the substantially flat-plate-shaped second magnet 90.
Alternatively, a substantially curved third end 544a on the lower side of the substantially rectangular annular coil 540 may be located below a lower end surface portion 84 of the substantially flat-plate-shaped first magnet 80 (not depicted), and a substantially curved fourth end 544b on the lower side of the substantially rectangular annular coil 540 may be located below a lower end surface portion 94 of the substantially flat-plate-shaped second magnet 90 (not depicted).
As depicted in FIG. 10, for example, when a portion of the actuator 505 is viewed laterally from inside to outside, if the substantially curved first end 543a on the upper side of the substantially rectangular annular coil 540 protrudes upward from the upper end surface portion 83 of the substantially flat-plate-shaped first magnet 80, and if the substantially curved second end 543b on the upper side of the substantially rectangular annular coil 540 protrudes upward from the upper end surface portion 93 of the substantially flat-plate-shaped second magnet 90, change in sensitivity is increased in the substantially curved ends 543a, 543b on the upper side of the substantially rectangular annular coil 540.
For example, when a portion of the actuator 505 is viewed laterally from inside to outside, if the substantially curved first end 543a on the upper side of the substantially rectangular annular coil 540 protrudes upward from the upper end surface portion 83 of the substantially flat-plate-shaped first magnet 80 and if the substantially curved second end 543b on the upper side of the substantially rectangular annular coil 540 protrudes upward from the upper end surface portion 93 of the substantially flat-plate-shaped second magnet 90, thrust is changed in the substantially curved ends 543a, 543b on the upper side of the substantially rectangular annular coil 540.
Alternatively, for example, when a portion of the actuator 505 is viewed laterally from inside to outside, if the substantially curved third end 544a on the lower side of the substantially rectangular annular coil 540 protrudes downward from the lower end surface portion 84 of the substantially flat-plate-shaped first magnet 80 (not depicted), and if the substantially curved fourth end 544b on the lower side of the substantially rectangular annular coil 540 protrudes downward from the lower end surface portion 94 of the substantially flat-plate-shaped second magnet 90 (not depicted), change in sensitivity is increased in the substantially curved ends 544a, 544b on the lower side of the substantially rectangular annular coil 540.
For example, when a portion of the actuator 505 is viewed laterally from inside to outside, if the substantially curved third end 544a on the lower side of the substantially rectangular annular coil 540 protrudes downward from the lower end surface portion 84 of the substantially flat-plate-shaped first magnet 80 (not depicted), and if the substantially curved fourth end 544b on the lower side of the substantially rectangular annular coil 540 protrudes downward from the lower end surface portion 94 of the substantially flat-plate-shaped second magnet 90 (not depicted), thrust is changed in the substantially curved ends 544a, 544b on the lower side of the substantially rectangular annular coil 540.
Those described above have significant influences on the thrust of the coil 540 for the magnets 80, 90, and the like, which is considered to be a problem.
For example, when a portion of the actuator 505 is viewed laterally from inside to outside, if the substantially curved first end 543a on the upper side of the substantially rectangular annular coil 540 protrudes upward from the upper end surface portion 83 of the substantially flat-plate-shaped first magnet 80, and if the substantially curved second end 543b on the upper side of the substantially rectangular annular coil 540 protrudes upward from the upper end surface portion 93 of the substantially flat-plate-shaped second magnet 90, a “deviation” occurs at a force application point that is the center of the force generated in the whole of the coil 540, for example, resulting in an effect on the vibration mode, etc., of the actuator 505, for example, which is considered to be a problem.
Alternatively, for example, when a portion of the actuator 505 is viewed laterally from inside to outside, if the substantially curved third end 544a on the lower side of the substantially rectangular annular coil 540 protrudes downward from the lower end surface portion 84 of the substantially flat-plate-shaped first magnet 80 (not depicted), and if the substantially curved fourth end 544b on the lower side of the substantially rectangular annular coil 540 protrudes downward from the lower end surface portion 94 of the substantially flat-plate-shaped second magnet 90 (not depicted), it is problematic that a “deviation” occurs at the force application point that is the center of the force generated in the whole of the coil 540, for example, and the vibration mode, etc., of the actuator 505, are affected for example, which is considered to be a problem.
Further reductions in the prices of the holding member 510, the driving apparatus 505, the pickup apparatus 503, and the disc apparatus are requested from the assembling makers that mount the pickup apparatuses 503 (FIG. 7) on optical disc apparatuses (not depicted), etc., for example, and the assembling makers that mount the optical disc apparatuses on personal computers (PC), etc.